Extruded Microstructures and Corrosion Properties of Biomedical Mg-6Zn-xGd Alloys

Abstract:

Extruded microstructures of Mg-6Zn-xGd (x=0~4) alloys were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). Meanwhile, the tensile mechanical property and corrosion property were tested. The results show that extruded microstructure is refined obviously increasing the Gd content, where the average grain size decreases from 12 ?m for Mg-6Zn alloy to 2 ?m for Mg-6Zn-3.41Gd alloy. Extruded tensile mechanical property is enhanced obviously. Tensile strength σb and yield strength σ0.2 increase gradually from 295 MPa and 193 MPa for Mg-6Zn alloy to 350 MPa and 325 MPa for Mg-6Zn-3.41Gd alloy. Elongation δ first decreases, and then increases, which is not lower than 10%. Extruded Mg-6Zn alloy exhibits the slow corrosion rate with typical local corrosion. When a little Gd content (0.66%) is added, the corrosion rate increases slightly, however its corrosion becomes more uniform and changes to the uniform corrosion. When more Gd content (1.66% and 3.41%) is added, the corrosion resistance deteriorates sharply.

Key words:biomedical magnesium alloy; Mg-Zn-Gd alloy; microstructure; mechanical property; corrosion resistance